However, this torture could not last always, he told himself. If it were she, he would know how to say things to her that must open her heart. Anything would be better than to be sure that she was not the Lady in Black, but some stranger who had never held him to her heart. But he must be certain--certain beyond any doubt, and he knew how to place himself in the presence of his memories of the Lady in Black, just as a dog is sure of finding its master. The simile which presented itself quite naturally to his imagination was simply that of “following the scent.” And this led us, under the circumstances which I have narrated, to Trepot and to Eu. However, it is by no means certain that decisive results would have been gained from this expedition--at least in the eyes of a third person, like myself--had it not been for the influence of the odor--if the letter from Mathilde, which I had handed to Rouletabille in the train, had not suddenly, with its faint, sweet perfume, brought to us directly the evidence which we were seeking. I have never read this letter. It is a document so sacred in the eyes of my friend, that other eyes will never behold it, but I know that the gentle reproaches which it contained for the boy’s rudeness and lack of confidence in the writer, had been so tender that Rouletabille could no longer deceive himself, even if the daughter of Professor Stangerson had not concluded the note with a final sentence, through which throbbed the heart of a despairing mother, and which said that “the interest which she felt in him arose less from the services he had rendered her, than because of the memories which she had of a little boy, the son of a friend, whom she had loved very dearly, and who had killed himself ‘like a little man with a broken heart’ at the age of nine years, and whom Rouletabille greatly resembled.” CHAPTER V PANIC Dijon--Macon--Lyons--certainly the boy could not be sleeping all this time. I called him softly and he did not reply, but I would have wagered my hand that he was not sleeping. What was he planning? How quiet he was! What could it be that had given him such a strange calmness? I seemed to see him again as he had been in the parlor, suddenly standing erect as he said: “Let us go on!” in that voice so composed and tranquil and resolute. Go on to whom? Toward what was he resolved to go? Toward Her, evidently, who was in danger, and who could be rescued only by him--toward her who was his mother and who did not know it. “It is a secret which must remain between you and me! That child is dead to the whole world, except to us two!”